Brilliance From Siggraph: Bokeh-Based Tiny Barcodes
"Bokeh" is a term used by photographers to praise the out-of-focus areas of a photograph.
Researchers at MIT have figured out how to exploit bokeh so that they can read 3mm barcodes with 2.5 micron elements at a distance of 4 meters with an off-the-shelf camera!
The "bokode" dot uses a lenslet to create lightrays which, when captured by a large aperture lens focused at infinity, reconstruct a pattern. The orientation of the bokode to the lens is highly recoverable. As a guy who just spent some time prototyping an augmented reality application and being foiled by the challenge of capturing exactly this information, I'm blown away.
More generally, I'm blown away by the transformation of "optics" into information processing. In my newfound hobby of astronomy, guys with 4" telescopes are creating images better than observatories could produce a few decades ago.